Protection of lamp controllers



Jan. 17, 1928;

. 1,656,321 E. DICK PROTECTION OF LAMP CONTROLLERS 2 Sheets-Sheet 1Filed May 5. 1924 All AlAAAll IIII II" M@LJV Jan, 17, 192s.

E. DICK.

PROTECTION OF LAMP CONTROLLERS Filed May 5. 1924 2 Sheets-Shee't 2Patented Jan. 17, 1928.

PATENT OFFICE.

EMIL DICK, OF GENEVA, SWITZERLAND.

PROTECTION OF LAMP CONTROLLERS.

Application filed May 5, 1924, Serial No. 711,021, and in Germany May 7,1923.

There are frequently employed, in connection with train-lighting systemsin which dynamos and storage-batteries are used, lampcontrollers thatefiect, in the network or circuit of the lamps, the maintenance of themost constant potential practicable. Essentially, the lamp-controllercomprises an electromagnet which is influenced by the lamp-potential andthe regulating member ofwhich suitably adjusts the quantity of theregulating resistance that is interposed in the lamp-mains. In this way,there is wiped out or neutralized the difference between theload-potential of the dynamo and the mean discharge-potential of thestorage-battery in the lamp-resistance through which the current flows.If, in the case of apparatus heretofore known, there should appear, inthe network of the lamps, an excess of current, which might, forexample, arise from a short circuit, this excessive current due to theshort circuit would flow through the lamp-controller and so would burnout the lamp-resistance and its contacts, as a result. This inventionhas for an object to protect the lamp-controller against the destructiveeffects of excessive currents. In the drawings illustrating theprinciple of this invention and the best mode now known to me ofapplying that principle, Fig. 1 is a diagrammatic (or schematic) view ofan apparatus adapted and designed to protect a lamp-controller from anoverload current; and Fig. 2 is a similar view showing a modified formof such an apparatus.-

The dynamo A is provided with an arma ture 1 and field-windings 2 and iscontrolled by an automatic regulator B having 'a regulating resistance 3and a contact 1 that is actuated by the solenoid 5, which is shown in ashunt circuit but which may, however, be energized by series current.For the adjustment of the controlled potential of the dynamo A, there isprovided the achustmg resistance 6. There is depicted likewise onlydiagrammatically the automatic circuitbreaker 7, which connects anddisconnects the dynamo A to and from the storage-battery 8 (or, ineffect, the network or bank'C of lamps 14), in case an equalization ofelec trical potential is to be or (as the case may be) is brought about.The lamp-controller D shown in Fig. 1 includes a regulating resistance 9which is interposed in one of the mains of the lamp-circuit and theregulating contact 10 of which is shifted automatically by the solenoid11 in a manner dependent upon the variations in the potential at thelamps let; while the lamp-controller D shown in Fig. 2 comprises fiveregulating resistances 9*. In series with the winding 1 the solenoid 11there isincluded an adjust ing resistance 12 which is about four timesas great as the resistance of the winding of the solenoid 11, and thepurpose of which is to compensate for the effect produced by the heatingof the latter. 13 denotes the main lamp-switch, by means of which thebank C of lamps let may, as need arises, be thrown into and out ofcircuit. 15 denotes fuses in the lamp-circuit.

For the protection of the lamp-controller D from a current overload,there is provided a relay E, which comprises an electromagnet on thecore E of which are mounted the shunt-winding 16 and the series-winding17. The shunt-winding 16 shown in Fig. 1 is subdivided and the terminalsof the sections are suitably connected with the lamp-regulatingresistance 9 by the connecting-wires 16, 16"; while the shunt-winding 16illustrated in Fig. 2 is not subdivided. To a lever 20 there arefastened the armature 18 ot the relay E and the yielding contacts 19,

away from the stationary contacts 22, 23,

against the magnetic pull of the electromagnct E, no excess current thenflowing through the lamp-regulating resistance 9. In case of a shortcircuit in the lamp-network (for example), there will flow a current ofexcessive intensity from the two sources of current (the dynamo A andthe storage-battery S, or from only the latter, as the case may be, ifthe dynamo A is cut out of circuit), through the lamp-regulatingresistance 9 to the place where theshort circuit exists; and, in thisevent, there appears, in the lamp-regulating resistance 9, a poten tialdrop that is determined by the intensity of the current due to the.short circuit and the ohmic resistance of the lamp-regulating resistance9 and which may be several times as great as the potential drop thereinpresent under normal working conditions. An inspection of Fig. 1 willshow that, as the contact 10 is pulled up by the solenoid 11 and isthereby shifted along the lamp-regulating resistance or rheostat 9, thecoils of the shunt-winding 16 are energized one after another, thelowermost coil, being first'energized, then the lowermost coil and themiddle coil together, and, finally, all three coils. By making asuitable selection of the number of turns and the resistances of thecoils of the shunt-winding 16 and by taking a suiiicient'number ofsuch'coils and properly choosing the points on the lamp-regulatingresistance 9 for the connection of wires leading thereto from thosecoils of the shuntwinding 16, it becomes practicable to arrange for theactuation of'the relay E due to a short circuit or to an overload in thenetwork C of lamps 14. .In case of an excessive current arising from ashort circuit or from an overload in the lamp-circuit C, the relay Eoperates in such manner that the greater the momentary or instantaneousresistance of the lamp-regulating resistance 9 is, the smaller is theexcess current required to actuate the lever 20 so as to bring thecontacts 19, 22, 23, together; and, at the instant of thiscontact-making, the lamp-regulating resistance 9 and the shunt-winding16' become short-circuited and the excessive current flows thereuponthrough the serieswindingl'? of the electromagnet E from which itresults that the latter continues energized and the contacts 19, 22, 23,remain closed so long as the flow of excessive current continues orpersists. In this attracted position of the relay-lever 20, theexcessive-current'is shunted aroundthe regulating resistance 9 so thatalmost none of the latter current flows therethrough. The shunt path ofthe excessive current is, naturally, the path of least resistance; andit may be traced asfollows: 1 to 7 to 20 to 19 to 22 to 17 to 13 to 15and thence tothe place where the short circuit-exists in thelampcircuit, and, from there, back to the other pole of the dynamo 1.Owing to the high resistance of the solenoid 11 as compared with that ofthe path of thecurrent through the place where the short circuit existsin the lamp-circuit, almost none of the excessive current flows throughthe coil 11. In this condition of the apparatus, in which the contacts19, 22, 23, are closed, the solenoid 11 is therefore made inoperative(or deener- 'gized)", to the end that the regulating-contact 10 isrestored by gravity to its initial lowermost position as rapidlyaspracticable, in which position the lamp-regulating resistance u 9 isshort-circuited. After the eradication of the short-circuit has beeneffected (as, for example, by the melting of one of the fuses 15), therevanishes also the excessive current, and simultaneously the lever 20 isjerked back to itsrest-position andrcarries with it thearmature 18 ofthe relay E, whereby the electrical contact existing between the parts19,22, 23, is destroyed or interrupted.

In Fig. 1, the lamp-regulating resistance or rheostat 9 is illustratedas a series-resistance, the'individual resistances of which are thrownvinto c1rcu1t one after another. Nevertheless, under certaincircumstances,

the parallel arrangement of the individual resistances of this rheostatis found more suitable for certain makesof lamp-controller. In Fig. 2,there is illustrated a lampcontroller D that comprises individualresistances 9 arranged'in' parallel. Each of the five lndivldualresistances 9 is connected, 1

on the one hand, to its own individual block or segment 24, and on theother hand, to a common bar 27. In addition there "is :provided aresistance 9', which diiiers,however,

from the resistances 9 in that itis not controlled. For the control ofthe resistances 9 there is provided a regulating member or lever 26 thatis fulcrumed at the point 25 and which is actuated by the solenoid 11and which, when so actuated, raises from the blocks 24 a certain numberof the yielding contacts 10*, the number thereof raised depending uponthe position assumed bythe controlling lever 26; bythis movement of thelatter, the resistance required at the particular instant is introducedinto the lamp-circuit C. The series-winding 17 that surrounds the coreof the electromagnet E" of the relay E" forms part of the main C of thetherethrough always flows through the magnet-winding 17 also. 7

lamp-circuit, "so that the current-flowing The gist or principle of thisinventionre- 2 sides in that there is employed or utilized for theautomatic short-circuitin'g of the lamp-regulating resistance, eitherthe current of excessively high intensity that flows temporarilythrough" the lamp-regulating resistance, or the abnormally greatpotential drop existing at the instant in that resistance,

or both this abnormally high current-intensity and excessively greatpotential drop; and that, after the operation of the relay, theexcessively high current is led over a short-circuit path; and that,after the shortthoroughly well understood that I intend to include.within the scope of the. claims that follow hereinafter all changesthat do not depart from the spirit of this invention. For example, thewinding 16 may bereplaced by one made up of series-wound and shunt-woundcoils or of only series-wound coils and. these coils maybesuitably-.jconmechanism controlling the same; a relay that is broughtinto action by the existence of an abnormal electrical condition at therheostat and by the acting of which said mechanism is renderedinoperative to permit said device to be returned to its initialposition; and a normally-open path that is closed by the acting of therelay to permit the passage of abnormal current around the 20 rheostat.

EMIL DICK.

